In the case of a photovoltaic device, in order to reduce manufacturing cost and improve efficiency, research into a technology of using various materials except for silicon has been conducted. However, due to characteristics of photovoltaic device using principles of semiconductors, a photovoltaic device made of other materials has low efficiency and a short lifespan due to degradation as compared to a photovoltaic device based on silicon, such that actual market share of the photovoltaic device made of other materials is only about 3%.
In the case of the photovoltaic device based on silicon, single crystalline silicon or polycrystalline silicon is mainly used, and cost of silicon material and wafer is more than 40% of the total construction cost at the time of construction of a photovoltaic system. Therefore, as a realistic solution, efforts to reduce an amount of silicon required to produce unit power by increasing photovoltaic efficiency using a silicon quantum dot and minimize consumption of silicon using a thin-film device have been made.
In manufacturing of the silicon quantum dot solar cell and silicon thin film solar cell as described above, growth of a silicon thin film doped with a semiconductor element is very important for improving performance of the solar cell. In the case of using the existing thermal diffusion method and chemical vapor deposition method, there is a limitation in adjusting a doping concentration, such that a special method for high density doping has been required.